1. Field of the Invention
The present invention relates to an outboard motor and, in particular, to an outboard motor including a rope reel on which an engine starter rope is wound.
2. Description of Related Art
European Patent Application Publication No. EP 1092866 A2, for example, discloses an outboard motor including a rope reel on which an engine starter rope is wound.
The outboard motor disclosed in EP 1092866 A2 is arranged such that the rope reel is rotated when a user pulls a handle portion of the rope. The rotation of the rope reel is transmitted to the crankshaft and thereby the engine is started. The pulled-out rope is to be rewound by a force provided by a rewind spiral spring.
However, when starting the engine by pulling the rope, the user is required to pull the rope with a force exceeding a friction or resistance maximized at the compression point of the engine (top dead center of the piston). This makes it difficult to start the engine.
In order to reduce the resistance at engine start, it may be considered to increase the diameter of the rope winding portion of the rope reel. However, the amount of revolution of the engine decreases relative to the amount of pulling the rope, resulting in poor startability. In addition, the size of the engine cover of the outboard motor increases.
On the other hand, United States Patent Application Publication Nos. US 2004/0177823A1 and US 2005/0199212 A1 each disclose a general-purpose engine starter including a force accumulation spiral spring in addition to a rewind spiral spring, although not arranged for use in outboard motors.
In the general-purpose engine starter disclosed in US 2004/0177823 A1 and US 2005/0199212 A1, when the rope is pulled and thereby the rope reel is rotated, the force accumulation spiral spring is wound to be accumulated with a force. The crankshaft is rotated by the force accumulated in the force accumulation spiral spring, and thus the engine is started. This arrangement allows the user to experience a reduced resistance when pulling the rope at the start of the engine without increasing the diameter of the rope reel.
In the arrangement disclosed in US 2004/0177823 A1 and US 2005/0199212 A1, the rope reel includes a plate portion rotatable about the rotational center axis of the crankshaft and a rope winding portion provided integrally with the plate portion at the peripheral edge thereof. The engine starter rope is wound around the rope winding portion. The plate portion is disposed between the force accumulation spiral spring and the rewind spiral spring. The force accumulation spiral spring is considered to be disposed closer to the engine with respect to the plate portion, although this is not described explicitly in US 2004/0177823 A1 and US 2005/0199212 A1.
In the arrangement disclosed in US 2004/0177823 A1, the height position of the plate portion is approximately the same as that of the rope winding portion. In the arrangement disclosed in US 2005/0199212 A1, the rope winding portion is extended toward the force accumulation spiral spring (i.e., toward the engine) from the plate portion by the width of the force accumulation spiral spring. Consequently, the rope winding portion is disposed closer to the engine than the force accumulation spiral spring.